The Family Braconidae is the second largest family of Hymenoptera (after of Ichneumonidae). More than 21200 species of this family have been described so far. The subfamily Microgastrinae with about 60 genera and more than 2700 species are known is one of the largest parasitoids of Lepidoptera. In addition, it is one of the most species-rich subfamilies of parasitoid wasps. The genus Microplitis Forster, 1862 is a very large genus of the tribe Microplitini and comprising more than 178 described species worldwide and 13 species have identified in Iran. There is tremendous biological diversity within the members of this genus including solitary, gregarious, idiobiont and koinobiont endoparasitoids of the host larvae and pupae. In this study, the specimens were collected from three provinces e.g., the Alborz, Tehran and Qazvin provinces during 2010 to 2011, using Malaise traps. Among the collected specimens from the Karadj area 1♂ in 22.vi.2010, at altitude of 1277 meters above sea level on geographical coordinates 35°46′08.88″ North and 50°56′55.20″ from the East, the Shahriar area (West of Tehran) 1♀ 15.vi.2010, at altitude of 1168 meters above sea level on geographical coordinates 35 ° 40'08.10"North and 50 ° 56'56.64" from the East and the Zereshk Road area 1♀ and 1♂ in 5.ix.2011, at altitude of 1541 meters above sea level on geographical coordinates 36°21′39.72″ North and 50°03′55.56″ from the East, the species Microplitis kaszabi Papp, 1980 was identified. This species just was recorded from the Eastern Palearctic previously. The morphological diagnostic characters of this species: Body length: 3.30–3.80 mm. Antenna as long as or longer than body length, flagellomere 15 of antenna nearly twice to more than twice as long as width; anteromesoscutum rugulose, notauli almost distinct with rugosity, scutellum with weak rugulose; length of stigma about 2.50× its wide, vein R1 distinctly longer than half length of stigma, length of 1st discal cell 1.20–1.30× its width, vein 1CUb 1.70–1.80× as long as vein 1CUa; T1 usually posteriorly with more or less broadening sides and length of that usually 1.50–1.60× its greatest width. Colouration: Black; Antenna brown; tegula, scape and T2 and T3 yellow to reddish yellow; stigma dark brown or black with a small basal yellow spot; legs exception of coxae reddish yellow to yellow. The biology and hosts of Microplitis kaszabi is unknown because sampling was done using Malaise trap. This species is new for the Iranian fauna and the collected specimens are deposited in the Collection of Department of Entomology, Tarbiat Modares University.